scholarly journals Cortisol advantage of neighbouring the opposite sex in utero

2018 ◽  
Vol 5 (9) ◽  
pp. 171636 ◽  
Author(s):  
R. Fishman ◽  
Y. Vortman ◽  
U. Shanas ◽  
L. Koren
Keyword(s):  
Lung Development ◽  
Reproductive Output ◽  
Sex Ratios ◽  
Female Offspring ◽  
In Utero ◽  
Costs And Benefits ◽  
Myocastor Coypus ◽  
Wildlife Species ◽  
Opposite Sex ◽  
Hair Testing

Population sex ratios naturally fluctuate around equality. It is argued that the production of an equal number of male and female offspring by individual parents should be favoured by selection, if all costs and benefits are equal. Theoretically, an even sex ratio should yield the highest probability for a fetus to be adjacent to a fetus of the opposite sex in utero . This may cause developmental costs or benefits that have been overlooked. We examined the physiological and developmental parameters associated with in utero sex ratios in the nutria ( Myocastor coypus ), an invasive wildlife species with a strong reproductive output. Using hair testing, we found that litters with even sex ratios had the highest average cortisol levels. Fetuses neighbouring the opposite sex exhibited longer trunks than those neighbouring the same sex, which might imply better lung development. Our results are the first, to our knowledge, to link intra-utero sex ratios and fetal cortisol and suggest that fetal cortisol might be a mechanism by which even sex ratios are maintained via developmental advantages.

scholarly journals A LIFE-HISTORY PERSPECTIVE ON SEXUAL SELECTION IN A POLYGAMOUS SPECIES

2019 ◽  
Author(s):  
Gao Ke ◽  
Michiel van Wijk ◽  
Zoe Clement ◽  
Martijn Egas ◽  
Astrid Groot
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Sperm Competition ◽  
Reproductive Output ◽  
Relative Fitness ◽  
Quadratic Model ◽  
Costs And Benefits ◽  
Bateman Gradient ◽  
Multiple Matings ◽  
Males And Females

Abstract Background Ever since Darwin, evolutionary biologists have studied sexual selection driving differences in appearance and behaviour between males and females. An unchallenged paradigm in such studies is that one sex (usually the male) signals its quality as a mate to the other sex (usually the female), who is choosy in accepting a partner. Here, we argue that in polygamous species these roles may change dynamically with the mating status of males and females, depending on direct reproductive costs and benefits of multiple matings, and on sperm competition. We test this hypothesis using a polygamous moth species, as in moths not males but females are the signalers and males are the responders. Results We found that multiple matings are beneficial as well as costly for both sexes. Specifically, the number of matings did not affect the longevity of males or females, but when paired with a new virgin mate every night for five nights, only 67% of the males and 14% of the females mated successfully in all five nights. The female’s reproductive output increased with multiple matings, although when paired with a new virgin male every night, additional matings beyond 3 decreased her reproductive output, so that the Bateman gradient for females fit a quadratic model better than a linear model. The male’s reproductive success was positively affected by the number of matings and a linear regression line best fit the data. Simulations of the effect of sperm competition showed that increasing last-male paternity increases the steepness of the male Bateman gradient and thus the male’s relative fitness gain from additional mating. Irrespective of last-male paternity value, the female Bateman gradient is steeper than the male one for up to three matings. Conclusion Our results suggest that choosiness in moths may well change throughout the mating season, with males being more choosy early in the season and females being more choosy after having mated at least three times. This life-history perspective on the costs and benefits of multiple matings for both sexes sheds new light on sexual selection forces acting on sexual signals and responses.

scholarly journals In utero administration of GABA promotes fetal lung development

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Narendranath Reddy Chintagari ◽  
Yang Wang ◽  
Dong Xi ◽  
Lin Liu
Keyword(s):  
Lung Development ◽  
Fetal Lung ◽  
In Utero ◽  
Fetal Lung Development

scholarly journals Recruitment sex ratios in gray-tailed voles (Microtus canicaudus) in response to density, sex ratio, and season

2003 ◽  
Vol 81 (8) ◽  
pp. 1306-1311 ◽  
Author(s):  
Monica L Bond ◽  
Jerry O Wolff ◽  
Sven Krackow
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Resource Competition ◽  
Sex Ratios ◽  
Female Offspring ◽  
High Population ◽  
Reproductive Value ◽  
High Population Density ◽  
Adult Sex Ratio ◽  
Sex Ratio Adjustment

We tested predictions associated with three widely used hypotheses for facultative sex-ratio adjustment of vertebrates using eight enclosed populations of gray-tailed voles, Microtus canicaudus. These were (i) the population sex ratio hypothesis, which predicts that recruitment sex ratios should oppose adult sex-ratio skews, (ii) the local resource competition hypothesis, which predicts female-biased recruitment at low adult population density and male-biased recruitment at high population density, and (iii) the first cohort advantage hypothesis, which predicts that recruitment sex ratios should be female biased in the spring and male biased in the autumn. We monitored naturally increasing population densities with approximately equal adult sex ratios through the spring and summer and manipulated adult sex ratios in the autumn and measured subsequent sex ratios of recruits. We did not observe any significant sex-ratio adjustment in response to adult sex ratio or high population density; we did detect an influence of time within the breeding season, with more female offspring observed in the spring and more male offspring observed in the autumn. Significant seasonal increases in recruitment sex ratios indicate the capacity of female gray-tailed voles to manipulate their offspring sex ratios and suggest seasonal variation in the relative reproductive value of male and female offspring to be a regular phenomenon.

Female and male costs of reproduction must be equal in dioecious Cape plant genus Leucadendron (Proteaceae)

2019 ◽  
Vol 67 (7) ◽  
pp. 517
Author(s):  
Jeremy J. Midgley ◽  
Adam G. West ◽  
Michael D. Cramer
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Output ◽  
Sex Ratios ◽  
Reproductive Allocation ◽  
Costs Of Reproduction ◽  
Male And Female

The Cape Leucadendron genus is dioecious, with extreme vegetative dimorphism displayed in some species – females having much larger leaves and fewer branches than males – whereas other species are monomorphic. Leucadendron is ecologically diverse, with some species with canopy stored seeds (serotiny) and others with soil stored seeds. These features mean that the Cape Leucadendron is an ideal genus to study the costs of reproduction for the different sexes in plants, and to determine whether vegetative dimorphism could be due to unequal costs. Here we use the unique aspects of the fire-prone Cape environment in which leucadendrons occur to show that the costs of sex must be equal between the sexes. Leucadendron populations are single aged because they only recruit after fires that kill all adults. Therefore, because the sexes have the same lifespans, they must have the same lifetime extent of vegetative versus reproductive allocation. Also, ecologically similar hermaphrodite Proteaceae co-exist with dioecious taxa. To co-occur, dioecious and hermaphrodite taxa must have the same mean post-fire fitness. This implies that dioecious females must have double the reproductive output that a co-occurring hermaphrodite has. This is only possible if the costs of reproduction are the same for the sexes and that the sexes use the same resources for reproduction. Finally, because males and female co-occur, they must be competitively equivalent to maintain natal sex ratios. These three factors suggest male and female allocate equivalently and therefore that vegetative sexual dimorphism is unlikely to be due to differences in allocation.

Tree densities and sex ratios in breeding populations of dioecious Central Amazonian Myristicaceae

1990 ◽  
Vol 6 (2) ◽  
pp. 239-248 ◽  
Author(s):  
David D. Ackerly ◽  
Judy M. Rankin-De-Merona ◽  
William A. Rodrigues
Keyword(s):  
Adult Population ◽  
Sex Ratios ◽  
Abundant Species ◽  
Partial Explanation ◽  
Canopy Tree ◽  
Breeding Populations ◽  
The Face ◽  
Opposite Sex ◽  
The Mean ◽  
Male To Female

ABSTRACTThe densities of the breeding populations and the sex of all flowering individuals were recorded for five dioecious canopy tree species of Central Amazonian Myristicaceae, in 11 study areas of the Minimum Critical size of Ecosystems Project totalling 22.5 ha. Adult population densities were extremely low, ranging from 0.38 to 1.61 ha–1 for the five species studied. In a 10 ha study plot the mean distance to the nearest flowering conspecific ranged from 48 to 100 m, while the mean distance to the nearest opposite sex conspecific was 147 m. The two most abundant species, Iryanthera macrophylla and Virola calophylla, both showed male-biased sex ratios, of 23:9 and 20:6, respectively. The size class distribution of males, females and non-flowering individuals in V. calophylla suggests that earlier reproductive maturation of male plants may provide a partial explanation for this bias. In I. macrophylla, since 95% of the individuals were observed flowering, the observed ratio is representative of the population, and may be caused by sex shifts from male to female. The low reproductive densities, combined with the skewed sex ratios and overlapping generations of these species, create very small effective breeding populations, placing species such as these at great risk in the face of deforestation and habitat fragmentation.

scholarly journals Large mothers, but not large fathers, influence offspring number in a caridean shrimp

2018 ◽  
Vol 96 (10) ◽  
pp. 1106-1113 ◽  
Author(s):  
D.E. Sganga ◽  
C. Tropea ◽  
M. Valdora ◽  
M.F. Statti ◽  
L.S. López Greco
Keyword(s):  
Reproductive Output ◽  
Growth Period ◽  
Female Offspring ◽  
Growth Increment ◽  
Adult Males ◽  
Lipid Concentration ◽  
Offspring Quality ◽  
Offspring Number ◽  
Males And Females ◽  
The Relationship

The relationship between parental mass and female reproductive output, as well as offspring quality, was studied in the red cherry shrimp (Neocaridina davidi (Bouvier, 1904)) under controlled laboratory conditions. Adult males and females of the same age were paired combining different shrimp masses. The number of hatched juveniles from large females was higher than that from small ones, but no influence of paternal mass was detected on this variable. Both the mass of newly hatched juveniles and their growth increment during a 60-day period were similar for all parental masses. Shrimps reached sexual maturity at the end of the growth period in all treatments, and their biochemical reserves (glycogen, lipid, and protein concentrations) were not associated with maternal and paternal masses. However, lipid concentration was higher in female offspring than in male offspring. The present results show that, unlike maternal mass, paternal mass had no effect on female reproductive output and offspring quality, suggesting that the contribution of males to offspring development was adequate regardless of male size.

scholarly journals Reproduction and Offspring Sex Ratios Differ Markedly among Closely Related Hyperparasitoids Living in the Same Microhabitats

2019 ◽  
Vol 32 (3) ◽  
pp. 243-251 ◽  
Author(s):  
Jeffrey A. Harvey ◽  
Lucas de Haan ◽  
Oriol Verdeny-Vilalta ◽  
Bertanne Visser ◽  
Rieta Gols
Keyword(s):  
Reproductive Success ◽  
Sex Ratios ◽  
Reproductive Traits ◽  
Female Offspring ◽  
Forest Edge ◽  
Cotesia Glomerata ◽  
Small Scale ◽  
Lifetime Reproductive Success ◽  
Closely Related Species ◽  
Offspring Sex

Abstract Closely related species in nature usually exhibit very similar phylogenetically conserved traits, such as reproduction, behavior and development. Here, we compared fecundity schedules, lifetime reproductive success and offspring sex ratios in three congeneric facultative hyperparasitoid wasps that exhibit several overlapping traits and which co-occur in the same small-scale habitats. Gelis agilis, G. proximus and G. hortensis are abundant in meadows and forest edge habitats in the Netherlands. Gelis agilis is asexual (all female), whereas the other two species reproduce sexually. Here they developed on cocoons of the primary parasitoid Cotesia glomerata. When provided with unlimited hosts, lifetime reproductive success was three times higher in G. proximus than in G. agilis with G. hortensis producing intermediate numbers of offspring. All three species depleted their teneral reserves during their lives. Females of G. proximus and G. hortensis lived significantly longer than females of G. agilis. Offspring sex ratios in young G. proximus mothers were female-biased and marginally male-biased in G. hortensis. As mothers aged, however, the ratio of male:female progeny produced rapidly increased until no daughters emerged later in life. Our results reveal significant differences in reproductive traits among the three species despite them co-occurring in the same microhabitats, being very closely related and morphologically similar. The increase in the production of male progeny by Gelis mothers over time suggests a depletion in sperm number or viability with age. This is especially interesting, given that Gelis species are among the least fecund parasitoids thus far studied. It is likely that in the field most Gelis mothers are probably only able to parasitize a few hosts and to maintain the production of female offspring.

scholarly journals Sperm sex ratio adjustment in a mammal: perceived male competition leads to elevated proportions of female-producing sperm

2020 ◽  
Vol 16 (6) ◽  
pp. 20190929
Author(s):  
Renée C. Firman ◽  
Jamie N. Tedeschi ◽  
Francisco Garcia-Gonzalez
Keyword(s):  
Sex Ratio ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Female Offspring ◽  
Male Competition ◽  
Offspring Sex ◽  
Sex Ratio Adjustment ◽  
Adaptive Adjustment ◽  
Male House

Mammal sex allocation research has focused almost exclusively on maternal traits, but it is now apparent that fathers can also influence offspring sex ratios. Parents that produce female offspring under conditions of intense male–male competition can benefit with greater assurance of maximized grand-parentage. Adaptive adjustment in the sperm sex ratio, for example with an increase in the production of X-chromosome bearing sperm (CBS), is one potential paternal mechanism for achieving female-biased sex ratios. Here, we tested this mechanistic hypothesis by varying the risk of male–male competition that male house mice perceived during development, and quantifying sperm sex ratios at sexual maturity. Our analyses revealed that males exposed to a competitive ‘risk’ produced lower proportions of Y-CBS compared to males that matured under ‘no risk’ of competition. We also explored whether testosterone production was linked to sperm sex ratio variation, but found no evidence to support this. We discuss our findings in relation to the adaptive value of sperm sex ratio adjustments and the role of steroid hormones in socially induced sex allocation.

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